Printing – Stenciling – Traveling-inker machines
Patent
1991-02-15
1992-09-22
Burr, Edgar S.
Printing
Stenciling
Traveling-inker machines
101120, 101124, B41L 1306
Patent
active
051487438
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This application is a National Phase application of PCT/AT90/0056 filed Jun. 6, 1990 and based upon Austrian National application A 1482/89 filed Jun. 16, 1989 under the International Convention.
The present invention relates to a coating machine with magnetically produced pressure of the doctor blade (squeegee). For the purposes of this description, a "coating machine" is a printing machine, e.g. a flat-bed screen printing machine or a drum-type screen printing machine, or also a full-surface coating machine, i.e. one which works on the entire surface without pattern printing. The substrate to be coated is a so-called web of material, i.e. a flat structure, for instance of textile material, paper, plastic material or the like, the substrate can for instance be also a carpet or another type of floor covering, wall covering or the like, a web of sheet metal or a transmission belt. In any case, the coating procedure takes place in connection with a relative motion of at least one of the application devices built into a coating machine of the invention and the substrate.
Since the element performing the coating is pressed by magnetic force against the substrate or the stencil it can be either a doctor roller, a spreading doctor blade, a spreading knife or the like, made of a magnetizable material or at least provided with parts of magnetizable material.
The basic aim of the invention is to place the web of material (substrate) in the coating machine so that it is flattened in the optimal position required by the coating process. This was, respectively is not possible according to the present state of the art, because in the coating machine the substrate web sags more or less, upstream or downstream of the application device. This sagging of the substrate web impairs the quality of the application process; this is particularly valid for application devices with magnetically operated doctor blades in flat-bed screen printing machines. In such printing machines, the coating process takes place alternately in two opposite travel directions. Therefore, in each travel direction and in each travel path section of each steep application stretch different sagging situations occur, which results in various contact portions, respectively contact times between the device generating the magnetic force, a narrow table -- it is also possible to use a magnetic roller instead of such a magnetic table -- and the bottom side of the stencil, which during the application process rests against the substrate web.
This functional disadvantage or construction drawback, cannot be eliminated or avoided either by stretching the substrate web in the coating machine or by providing the coating machine with an endless conveyor belt supporting the substrate. The known physical laws relating to catenaries.
BACKGROUND OF THE INVENTION
Application devices with magnetic tables for printing machines are known in a variety of construction types, so that a detailed description can here be omitted.
The fact that coating machines equipped with magnetically operated application devices, particularly flat-bed screen printing machines of the aforedescribed construction have been known for decades and are widely introduced on the world market and in use, and that during this time a great deal of effort has been invested in order to efficiently eliminate the aforedescribed construction and operation drawbacks without leading to a satisfactory solution, proves the need for improvement.
SUMMARY OF THE INVENTION
This is characterized in that in a coating machine equipped with at least one magnetically operated application device, or a doctor blade device of the kind known per se and in any case having also a conveyor belt, at least one support strap or a profiled section is held or stretched at the ends and cooperating with a magnetic table or the like, equipped with at least one element generating magnetic force. The upper side of this support strap or profiled section strapped into the coating machine is arran
REFERENCES:
patent: 3196784 (1965-07-01), Kraft
patent: 3216349 (1965-11-01), Kraft
patent: 4090443 (1978-05-01), Gasser
patent: 4557194 (1985-12-01), Zimmer
Burr Edgar S.
Dubno Herbert
Raciti Eric P.
Wilford Andrew
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